Article Arq Neuropsiquiatr 2010;68(2):174-178
Emergency EEG Study of survival Moacir Alves Borges1, Harethusa Junia Botós2, Ricardo Funes Bastos2, Moacir Fernandes Godoy3, Nely Silvia Aragão de Marchi1 Abstract Objective: To determine the survival rate according to the main findings of emergency electroencephalography (EEGs) of patients treated in a tertiary hospital. Method: In this prospective study, the findings of consecutive emergency EEGs performed on inpatients in Hospital de Base in São José do Rio Preto, Brazil were correlated with survival utilizing KaplanMeyer survival curves. Results: A total of 681 patients with an average age of 42 years old (1 day to 96 years) were evaluated, of which 406 were male. The main reasons for EEGs were epileptic seizures (221 cases), hepatic encephalopathy [116 cases of which 85 (73.3%) were men, p-value=0.001], status epilepticus (104 cases) and impaired consciousness (78 cases). The underlying disease was confirmed in 578 (84.3%) cases with 119 (17.5%) having liver disease [91 (76.0%) were men, p-value=0.001], 105 (15.4%) suffering strokes, 67 (9.9%) having metabolic disorders, 51 (7.5%) central nervous system infections and 49 (7.2%) epilepsy. In the three months following EEG, a survival rate of 75% was found in patients with normal, discreet slow activity or intermittent rhythmic delta activity EEGs, of 50% for those with continuous delta activity and generalized epileptiform discharges, and of 25% for those with burst-suppression, diffuse depression, and in alpha/theta-pattern coma. Death was pronounced immediately in patients with isoelectric EEGs. Conclusion: The main findings of EEGs, differentiated different survival rates and are thus a good prognostic tool for patients examined in emergencies. Key words: EEG, emergency, prognosis, probability of survival. EEG de urgência: taxa de sobrevivência
Correspondence Moacir Alves Borges Rua Nair do Santos Lima 110 15090-290 São José do Rio Preto SP - Brasil E-mail
[email protected] Received 17 February 2009 Received in final form 19 October 2009 Accepted 30 October 2009 174
Resumo Objetivo: Determinar a taxa de sobrevivência (TS), segundo os principais achados de eletrencefalograma de urgência (E-EEG), dos pacientes atendidos nas emergências de hospital de alta complexidade. Método: Estudo prospectivo, por ordem de chegada, da correlação entre os achados de E-EEG, feitos nos pacientes à beira do leito, com TS, utilizando-se as curvas de sobrevidas de Kaplan Meyer no Hospital de Base de São José do Rio Preto, São Paulo/Brasil. Resultados: Foram estudados 681 pacientes, dos quais 406 (59,6%) masculinos, com idade média de 42 anos (1 dia a 96 anos). As principais motivações para o E-EEG foram crises epilépticas (221 casos), encefalopatia hepática [(116 casos, dos quais 85 masculinos (73,3%), p= 0,001]; estado de mal epiléptico 104 e rebaixamento de consciência 78. O diagnóstico da doença de base foi confirmado em 578 (84,3%), sendo 119 (17,5%) hepatopatia, dos quais 91 (76,%) masculinos, p= 0,001; 105 (15,4%) acidente vascular encefálico; 67 (9,9%) distúrbio metabólico; 51 (7,5%) infecção do sistema nervoso central e 49 (7,2%) epilepsia. TS de 75% nos três primeiros meses foi encontrada nos pacientes com E-EEG com alentecimento discreto ou com atividade delta rítmica intermitente. TS por volta de 50% nos três meses foi encontrado nos pacientes com E-EEG com delta contínuo, crítico e com descargas periódicas. A TS foi menor que 25% nos dois primeiros meses após E-EEG, nos pacientes com E-EEG com surto/supressão, com depressão difusa e com comas alfa/teta e 0% nos E-EEG iselétricos. Conclusão: O E-EEG, com seus principais achados, foi capaz de diferenciar as diversas taxas de sobrevivências na amostra estudada, constituindo-se, portanto, bom instrumento de prognóstico para pacientes atendidos nas unidades de emergência hospitalar. Palavras-chave: EEG, emergência, probabilidade de sobrevida. 1
PhD, Professor, Neuroscience Department of the Medicine School in São José do Rio Preto, São José do Rio Preto SP, Brazil; MD, Resident, Neuroscience Department of the Medicine School in São José do Rio Preto, São José do Rio Preto SP, Brazil; 3 PhD, Professor, Cardiology Department of the Medicine School in São José do Rio Preto, São José do Rio Preto SP, Brazil. 2
Arq Neuropsiquiatr 2010;68(2)
Emergency departments and intensive care units (ICU) are becoming increasingly more important in hospitals. Within the enormous range of tools available in these sectors, emergency electroencephalography (EEG), due to its low cost, the time required to carry out the examination, the lack of risk and personnel requirements, contributes greatly to the treatment of patients with acute diseases, in particular those with changes in consciousness1-3. The different patterns of EEG obtained in emergency patients, although nonspecific, can often be correlated with the etiology of diseases of the central nervous system such as trauma4, vascular injury and anoxic-ischemic injury due to cardiorespiratory arrest5. In hepatic encephalopathy6,7, Creutzfeldt-Jakob disease8, non-convulsive status epilepticus9-15 and herpes simplex encephalitis16, EEG is decisive for diagnosis and thus guides therapy and gives an indication of the prognosis. EEG also contributes by characterizing the state of consciousness in exogen intoxication and metabolic encephalopathy17,18. Hence, EEG has gained importance in the identification of cases with persistently reduced consciousness but with normal imaging examinations4,18. This study aimed at correlating survival to emergency EEG findings in patients examined in a tertiary hospital. Method This is a prospective study of emergency EEGs obtained from patients submitted to urgent examinations in the Emergency Department, on the ward or in intensive care units (ICUs) of Hospital de Base in São José do Rio Preto. Hospital de Base is a tertiary hospital and regional reference center with 716 beds, 155 of which are in ICUs. The Emergency Department attends an average of 9,700 patients per month. The emergency EEGs were performed in the laboratory of neurophysiology or at the bedside. Electrodes were placed according to the 10/20 international system utilizing two Berg analogue apparatuses (time constant: 0.3; filter: 70 Hz; notch filter: 60 Hz; paper speed: 3 cm/ second) with eight channels and two Nihon digital apparatuses (12-bit) with 22 channels. Only the first emergency EEG examination of each patient studied between 1/7/06 and 1/8/07 was included in this work, although some patients were submitted to as many as 10 examinations. The results were interpreted by two experienced neurophysiologists (MAB, NSAM) assisted by two trainees (HJB, FRB), with the final decision being by consensus. Patients with diagnoses from previous hospitalizations, those with technically low quality examinations and patients for whom consent to participate was refused by the next of kin were excluded from the study. For study purposes, only the most significant alteration, whether related to the baseline rhythm or paroxis-
Emergency EEG: survival Borges et al.
tic disorders, was considered in each EEG; some examinations had more than one evident alteration. Thus, only one emergency EEG result was analyzed for each patient. The following findings were standardized according to the modified criteria of Husain3: 1) intermittent rhythmic delta activity (IRDA); 2) critical activity epileptiform according to Treiman et al.19 with modifications by Garzon et al.20; 3) normal; 4) burst-suppression; 5) continuous high-voltage delta activity according to Amodio et al.7; 6) low-voltage, slow, nonreactive EEG of less than 10 mV; 7) diffuse periodic epileptiform disorder (PED) and lateralized (PLED); 8) coma with specific rhythms (alpha, theta and spindle); 9) electrocerebral inactivity (according to the minimum technical requirements proposed by the American Clinical Neurophysiology Society and 10) intercritical epileptiform disorder. The data were obtained and stored in an Excel spreadsheet. Diagnosis of the underlying disease was made by investigating the clinical history, even if precarious, complementary biochemical examinations, imaging examinations such as computed tomography and magnetic resonance, as well as the diagnosis confirmation service, that is, autopsy. Epilepsy was diagnosed only when epileptic seizures occurred, without being caused by any acute disorder, on more than two occasions with an interval of more than 24 hours. Generalized convulsive status epilepticus (GCSE) was defined according to the Commission of Classification and Terminology of the International League against Epilepsy21, with modifications by Lowenstein et al.22 and Brenner14. The Pearson chi-square or Fisher exact tests were utilized in the statistical analysis of the gender, age and sample data. Kaplan-Meyer curves23 were employed to estimate survival probabilities. To compare survival curves, the Log-rank test and empirical Hazard function were used. The event of death was considered after confirmation by autopsy, the data of which was registered in the patient’s hospital records or was obtained by telephoning the relatives of the deceased. Surviving patients, who did not return to the outpatient’s clinic within three months after release from hospital, were also contacted by telephone to check on their health. The level of statistical significance was set at 0.05. Results A total of 712 cases were considered however only 681 filled the inclusion criteria of this study. Of these, 406 (59.6%) were men (p-value=0.001). The ages had a nonGaussian bimodal distribution with peaks for patients within the first year of life and for those between 50 to 70 years old. The average age was 42 years old (range: 1 day to 96 years old – Fig 1). The data of 48 (7%) cases were not updated from the 175
Emergency EEG: survival Borges et al.
Arq Neuropsiquiatr 2010;68(2) Histogram of age Normal
Hepatic encephalopathy Unknow Stroke
120
Central nervous system infection Epilepsy
100
Newborn disorder
Frequency
80
Heart disease Head-brain injury
60
Brain tumor Renal failure
40
Diabetes Alcoholism
20
Chronic respiratory insufficiency Alzheimer’s disease
0
–20
0
20
40
Mean=42.98
60
80
StDev=27.81
100
Acute abdomen Central nervous system malformation Psychogenic non-epileptic seizures
N=681
Drowning Poisoning
Fig 1. Distribution of the patients who underwent E-EEG.
Creutzfeld-Jakob disease 0
patients records or by telephone) in the three months following the last day for patient enrollment (1/8/2007). The reasons to perform emergency EEGs are shown in Table. The underlying disease was elucidated in 578 (84.3%) of the participating patients whose main diseases are shown in Figure 2. Among the 119 (17.5%) patients who suffered hepatic encephalopathy, 26 (21.9%) presented with triphasic waves. The survival curves of the ten most common electroencephalographic findings are shown in Figure 3. Discussion The current study was designed to evaluate survival in respect to emergency EEG findings of patients exam-
20
40
60 F
80
100
M
Fig 2. The main diseases found correlated with gender;*pvalue= 0.001
ined in a tertiary general hospital. Performing emergency EEGs is feasible24 however subject to many artifacts as was commented in the excellent review article published by Kaplan25. To reduce artifacts, ICUs have been adapted to local specifications with adequate earthing being provided for the apparatuses. Even so, whenever possible, when there was no risk of life, the patients were transferred either in wheel chairs or on stretchers to the neurophysiology laboratory. The first interesting data found in this study was that
100 critical delta continuous
80
inactivity intercritical IRDA low-voltage
60 Percent
normal PED specific rhythms
40
SS
20
0
0
100
200
300
Time to death (days)
176
400
Fig 3. Survival curve of patients attended in emergency units of Hospital de Base according to the ten most common electroencephalographic finding. Critical: critical activity epilepcticus; IRDA: intermittent rhythmic delta activity; PED: periodic epileptic form disorder; SS: burst-suppression. Relationship among curves p-value=0.001.
Emergency EEG: survival Borges et al.
Arq Neuropsiquiatr 2010;68(2) Table. Reasons to perform the E-EEG correlated to gender (n=681). M*
F**
Reason
n
%
n
%
Seizure
131
59.3
90
40.7
Hepatic encephalopathy#
85
73.3
31
26.7
Reduction in awareness
49
62.8
29
37.2
CSE
45
46.4
52
53.6
Coma
21
53.8
18
46.2
CRA
25
60
10
40
Brain death
14
66.7
7
33.3
Stroke
6
64.7
11
35.3
Mental confusion
6
37.5
10
62.5
Miscellanea3
7
50
7
50
Encephalitis
7
63.6
4
36.4
HBI
7
63.6
4
36.4
PNEE5
3
60
2
40
Total
406
59.6
275
40.4
1
2
4
#
convulsive status epilepticus; 2cardiorespiratory arrest; 3apnea, Parkinson disease, abstinence, tremor, poisoning; 4head-brain injury; 5psychogenic non-epileptic event. *male; **female; #p-value
